In recent years, handheld medical imaging transceivers, such as ultrasound and gamma ray transceivers, have been used extensively for various medical imaging situations. In certain procedures, such as biopsies, it may be desired to tilt a needle with respect to a needle guide or vice versa.
In the past, the physician or medical professional may be required to detach a biopsy needle from a needle guide prior to changing the angle of the needle with respect to the needle guide and transceiver. Other prior art needle guides have included a pair of spaced-apart fixed parallel plates. The medical professional could place the needle between the parallel plates, and it would be free in a plane parallel with the plates, but restricted from large movements outside that plane.
Other prior art needle guides have been used which include a resilient tube coupled to a transducer where the tube has a longitudinal slit through which the needle can be pulled when relative tilting is required.
While these needle guides have been used extensively in the past, they do have some drawbacks. First of all any model of fixed parallel plate needle guide is limited in the size of needle that can be guided therein. If the needle is too big, it will not fit between the fixed parallel plates. If the plates are too far apart, there is less support being provided in the desired direction. Also, these parallel plate needle guides only provide support in one direction. They provide no support or resistance from motion within the plane of the parallel gap between the fixed plates. This increases the attention required by the medical professional.
Secondly, the resilient slit tube type of needle guide does provide some resistance to motion in the desired plane of motion, but it is limited to only the first portion of that movement or motion. Once the needle is tilted out of the tube, there is no support or resistance to motion in any direction. Additionally, these types of needle guides will work only with specific gauges of needles. They will not work well when a narrow gauge needle is used in a needle guide primarily designed for a larger needle. The narrower needle may fall through the slit. Conversely, a larger needle may not fit in the tube, or it may be difficult to pull through the slit. Consequently, numerous sized slit tube needle guides would be needed to fulfill the needs of a medical professional who uses needles of varying sizes. Additionally, these slit tube type of needle guides may be viewed as unstable in the direction of relative motion. For example, the force required to be applied to the needle to move the needle in the tilted direction decreases as the amount of tilting occurs. To assure that excess tilting does not occur, the medical professional needs to give more attention to the force being applied when the required force decreases with angular displacement.
Consequently, there exists a need for improved methods and apparatus for guiding needles in an efficient manner.